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fargo 1a822493ba format: apply repo prettier (3.8.1) to the folded skills tree

963 markdown files reformatted with the repository's pinned prettier so
pnpm format:check covers the folded tree like every other repo file.

The formatter's embedded-language pass also normalized code fences
(TS semicolons, closed HTML tags in examples, lowercased CSS hex colors,
one renumbered list that skipped an index). Alphanumeric token deltas vs
the fold commit were audited file-by-file; all are formatter-equivalent
markup normalizations plus the four sanitized skills.

2026-08-19 14:37:17 -05:00

3.6 KiB

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Target Environment

Configure JavaScript syntax transformations for target environments.

Overview

The target option controls which JavaScript features are downleveled (transformed to older syntax) for compatibility.

Important: Only affects syntax transformations, not runtime polyfills.

Default Behavior

tsdown auto-reads from package.json:

// package.json
{
  "engines": {
    "node": ">=18.0.0"
  }
}

Automatically sets target to node18.0.0.

If no engines.node field exists, behaves as if target: false (no transformations).

Disabling Transformations

Set to false to preserve modern syntax:

export default defineConfig({
  target: false,
});

Result:

No JavaScript downleveling
Modern features preserved (optional chaining ?., nullish coalescing ??, etc.)

Use when:

Targeting modern environments
Handling transformations elsewhere
Building libraries for further processing

Setting Target

CLI

# Single target
tsdown --target es2020
tsdown --target node20

# Multiple targets
tsdown --target chrome100 --target node20.18

# Disable
tsdown --no-target

Config File

export default defineConfig({
  entry: ['src/index.ts'],
  target: 'es2020',
});

Multiple Targets

export default defineConfig({
  entry: ['src/index.ts'],
  target: ['chrome100', 'safari15', 'node18'],
});

Supported Targets

ECMAScript Versions

es2015, es2016, es2017, es2018, es2019, es2020, es2021, es2022, es2023, esnext

Browser Versions

chrome100, safari18, firefox110, edge100, etc.

Node.js Versions

node16, node18, node20, node20.18, etc.

Examples

Modern Browsers

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm'],
  target: ['chrome100', 'safari15', 'firefox100'],
});

Node.js Library

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm', 'cjs'],
  target: 'node18',
});

Legacy Support

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm'],
  target: 'es2015', // Maximum compatibility
});

Per-Format Targets

export default defineConfig({
  entry: ['src/index.ts'],
  format: {
    esm: {
      target: 'es2020',
    },
    cjs: {
      target: 'node16',
    },
  },
});

Decorators

Legacy Decorators (Stage 2)

Enable in tsconfig.json:

{
  "compilerOptions": {
    "experimentalDecorators": true
  }
}

Stage 3 Decorators

Not currently supported by tsdown/Rolldown/Oxc.

See oxc issue #9170.

Common Patterns

Universal Library

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm', 'cjs'],
  target: 'es2020', // Wide compatibility
});

Modern-Only Library

export default defineConfig({
  entry: ['src/index.ts'],
  format: ['esm'],
  target: false, // No transformations
});

Browser Component

export default defineConfig({
  entry: ['src/index.tsx'],
  format: ['esm'],
  target: ['chrome100', 'safari15', 'firefox100'],
  platform: 'browser',
});

Tips

Let tsdown auto-detect from package.json when possible
Use false for modern-only builds
Specify multiple targets for broader compatibility
Use legacy decorators with experimentalDecorators
Test output in target environments

Platform - Runtime environment
Output Format - Module formats
Minification - Code optimization

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